Cleaning my heat exchanger

[pcatterall]

I recently bought a spare heat exchanger to 'do up' and swap with the one on the boat ( in Spain).
I find it is a Serck exchanger and cannot locate spare parts ( its for a 1974 Perkins)
Hopefully all I need will be 2 O rings.
The inside of the tubes all look clean but I suspect there are deposits on their raw water surfaces
I will try to gently remove the stack but if I cant do this can I use a chemical to dissolve the deposits?
If so what is recommended for salt water scaling ( same as toilets?) and are there any tips on its use.
Assuming it all goes together Ok are there any tips on painting the body which is an alloy and showing
external corrosion and also the ends which appear to be bronze or brass.
Thanks

 

[NormanB]

1. Citric Acid solution.
2. O rings if you can identify the size and section you should be able to source on the interweb. Failing that as long as you can get hold of a 'bigger' one you can cut it down and superglue to size. Loctite used to sell a kit of long lengths of seal sections and a jig to assist cutting accurately.
3 Some systems also have an anode fitted in the cooler.

I cannot advise on the painting.

 

[Falling Star]

Search ebay for "Gun Cleaning Kit" £6.99 inc. p&p

Works well

 

[PaulRainbow]

Rydlyme : http://www.ricoservices.co.uk/environmentallyfr.htm

Ref paint, Hammerite special metals primer, followed by some smooth hammerite.

 

[Piers]

+1 for Rydlyme.

This is what I did when descaling Play d'eau's heat exchangers: http://www.playdeau.com/descaling-the-heat-exchanger/

 

[Vegable]

Did mine last week and used phosphoric acid. Sold in decorating shops as a passivater for painting galvanised steelwork. It's a pale to medium blue colour.
It hadn't been cleaned since new, 8 years ago and took an afternoon to clean. Stood it vertically in an old measuring jug.
I was also told you can use hydrochloric acid sold as brick and concrete cleaner in B&Q, but that is a stronger solution.
Mike

Editted bit. My heat exchanger was in a Volvo Penta and the 4 "O" rings were £12.34 EACH!!!! I've since found out the ASAP Supplies have a big stock of O rings and seals. You might try e mailing them a description of what you want.
Mike

 

[oldgit]

An old fender with an end cut off is ideal to marinate your heat exchanger core.Leave the eye for rope attached in order to hang it up vertically
I used a quick soak in Wickes brickcleaner to finally sort a persistant overheat when all the propietory marine descalers simply were not man enough to dissolve the crud on my Perkins M135 tubes.

 

[vyv_cox]

Most acids will effectively remove insoluble seawater salts, mostly magnesium carbonate but with smaller amounts of calcium carbonate and a few others. In general the metals used for heat exchanger construction are not going to be affected by short-term immersion in any acids, although if by any chance some of it was constructed of aluminium I would test it first. It then comes down to how long you want it to take. Organic acids like citric will do the job eventually but it will take an age. We used to use citric to remove rust from metallurgical samples but it took at least 12 hours. At the other end of the scale is hydrochloric acid, in most cases immersion for 10 minutes will have all deposits dissolved. All the others mentioned will do the job but a bit slower and in some cases a lot more expensively.

 

[geem]

Most acids will effectively remove insoluble seawater salts, mostly magnesium carbonate but with smaller amounts of calcium carbonate and a few others. In general the metals used for heat exchanger construction are not going to be affected by short-term immersion in any acids, although if by any chance some of it was constructed of aluminium I would test it first. It then comes down to how long you want it to take. Organic acids like citric will do the job eventually but it will take an age. We used to use citric to remove rust from metallurgical samples but it took at least 12 hours. At the other end of the scale is hydrochloric acid, in most cases immersion for 10 minutes will have all deposits dissolved. All the others mentioned will do the job but a bit slower and in some cases a lot more expensively.

+1
Did my spare heat exchanger off the generator with hydrochloric acid. The tubes were heavily coated with a white deposit. They were shiny copper clean in 5-10 mins. Quite impressive!

 

[PaulRainbow]

Rydlyme can be used to do the whole system, as in Piers link, without disassembly. (Yes, i know the OP is doing the heat exchanger separately.

 

[pcatterall]

Thanks all. I will have a go with brick cleaner. I see that it comes diluted to 16%. Perhaps after using it and giving it a good wash out it may help free the tube stack. The tubes inside do look good so I guess there was a good inhibitor being used?

 

[VicS]

Thanks all. I will have a go with brick cleaner. I see that it comes diluted to 16%. Perhaps after using it and giving it a good wash out it may help free the tube stack. The tubes inside do look good so I guess there was a good inhibitor being used?

If by 16% they mean 16% of HCl in water then that is half way to being concentrated hydrochloric acid. ! What brick cleaner are you looking at?

I'd dilue that 5 or even 10 fold for general light descaling

Id not use hydrochloric acid on an aluminum alloy.

My preference for your HE would be a sulfamic acid based descaler such as Fernox DS3 ( which you should find at plumbers merchants and many hardware and DIY stores)

Sulfamic acid is much stronger that the organic acids, such as citric acid, but not as strong as the strong mineral acids, such as hydrochloric acid

 

[pcatterall]

Thanks VicS The 16% came from the spec on one of the brick cleaning products from a builders merchant. The advice was dilute 4 to 1 for general use and 'neat' for heavy staining.

Your Sulfamic acid suggestion is noted and something slightly less aggressive than HCl is preferred. I was/am planning to still test on the outside of the body.

I had though about 'Fernox' which I have and do use for central heating but thought that while it was fine for inside fresh water systems ( de rusting etc) it might not be so effective on the raw water side?
Anyway I have some so I can try it!

Thanks again

PS Great video by the way.....sobering!

 

[VicS]

I had though about 'Fernox' which I have and do use for central heating but thought that while it was fine for inside fresh water systems ( de rusting etc) it might not be so effective on the raw water side?
Anyway I have some so I can try it!

There are numerous Fernox products. DS3 is a limescale remover. DS40 is citric acid based and may be more effective against rust and other iron oxide deposits in central heating systems as well as carbonate scaling.

I'd only use hydrochloric acid or hydrochloric acid based masonry cleaners as a last resort against heavy scaling and then only if I was sure that it was not going to attack any of the system components .


Rydlyme remains a mystery to me. HCl based but the concentration needed to remove the weight of scale claimed does not tally with the quoted pH figures. I wish I was still in a position to look at it in a lab or ask the analytical chemists to look at it.

 

[typhoonNige]

As it's only the raw water side that is likely to scale up I added Killrock kettle descaler (formic acid) to the water strainer, closed the raw water seacock and turned the engine over until the strainers contents had gone. After the fizzing and bubbling from the heat exchanger stopped I flushed it out by running the engine. Water flow from the exhaust was much improved afterwards. Anything wrong with this method, apart from the relative price of the Killrock?

 

[pcatterall]

I have just used a formic acid descaler which I happened to have around. It seems to have removed a lot of the build up but not some of the heavy scaling. I might have to try the DS3 but note that I have to buy 2kg for around £25.

 

[Ian_Rob]

To circulate Rydlyme though the heat exchanger of a Volvo D1-30B I had assumed is was necessary to connect the return to the outlet at the back of the HE that links to the Exhaust Elbow. Can one instead just link to the exhust elbow?

 

[VicS]

To circulate Rydlyme though the heat exchanger of a Volvo D1-30B I had assumed is was necessary to connect the return to the outlet at the back of the HE that links to the Exhaust Elbow. Can one instead just link to the exhust elbow?

No responses so far to your question. Perhaps you should have started your own new thread,

Looking at the documentation I suspect it will be difficult to remove the right angled outlet hose without also removing the exhaust elbow. The w/s manual shows them being removed together! If so this may influence your decision as to whether to connect directly to the HE outlet or not.

If you decide to connect the return to the exhaust elbow be careful not to obstruct the flow or you could flood the manifold and get Rydlyme into the engine.

How are you going to circulate the Rydlyme ?

 

[PaulRainbow]

How are you going to circulate the Rydlyme ?

I used a Whale Supersub bilge pump in a bucket when i did mine. But i fitted it to the engine room afterwards, or it might be considered an expensive way of descaling.

 

[Ian_Rob]

No responses so far to your question. Perhaps you should have started your own new thread,

Looking at the documentation I suspect it will be difficult to remove the right angled outlet hose without also removing the exhaust elbow. The w/s manual shows them being removed together! If so this may influence your decision as to whether to connect directly to the HE outlet or not.

If you decide to connect the return to the exhaust elbow be careful not to obstruct the flow or you could flood the manifold and get Rydlyme into the engine.

How are you going to circulate the Rydlyme ?

Yes, exactly. It is virtually impossible to remove the hose without destroying it and as per my earlier thread, I still can't undo the last nut on my Heat Exchanger. A Volvo dealer has quoted £58.00 + VAT to undo it for me but before committing to this I thought I would just check out the feasibility of connecting the return to the exhuast elbow instead. Basically you confirm my fear regarding Rydlyme getting into the engine so I will get the engineer to remove the elbow and show me the trick of how it's done at the same time. I need to clean the elbow as well so no bad thing to finally be able to remove it. Thanks for your help.

PS I have got a Whale Gulper.